94 Fawcett, Wain, and Wightman 



find in the experiments that he's just related to us — indole-3-acrylic 

 acid and indole-3-carboxylic acid. Indole-3-acrylic acid is a normal 

 component of human urine as its glycine derivative. The small 

 amount in all human urine from subjects on a normal mixed diet 

 disappears on fruit-free and plant-free diets. It must be derived from 

 some unknown indolic component, probably with a 3-carbon side 

 chain, present in plant or fruit products. It is not derived from tryp- 

 tophan, because a single subject can take as much as 10 g. of oral tryp- 

 tophan (a procedure I don't recommend) without causing any indole- 

 3-acrylic acid or its derivative to appear in the urine. But it is found 

 in urine if Dr. Wightman's compound indole-3-propionic acid is fed, 

 as reported by Decker. Indole-3-propionic acid has never been found, 

 as far as I'm aware, in plants, but it may have some precinsor which 

 may give rise to it on ingestion. Another possibility, currently being 

 investigated with Dr. K. N. F. Shaw, is that indole-3-pyruvic acitl 

 gives rise to the acrylic acid. Indole-3-pyruvic acid has had a check- 

 ered history in this connection, and it may be that there is some 

 plant component other than tryptophan which gives rise to indoIe-3- 

 pyruvic acid, say through the action of bacteria in the gut, and from 

 that to indole-3-acrylic acid. These are probably acetic materials. 

 They may be auxins, we do not know. 



There are a lot of indoles which occur in plants which may well 

 have important influences on animal metabolism. Serotonin is found 

 in many plants, in banana fruit for example, in tremendous amounts 

 ])hysiologically speaking, together with smaller amoiuits of related 

 amines; tomato contains a large amount of tryptamine, which wdll 

 normally give rise to indole-3-acetic acid. 



At the National Institutes of Health, w^e are giving drugs to pa- 

 tients to prevent or divert the normal oxidative metabolism of amines 

 including tryptamine and serotonin. If patients on these drugs eat 

 a lot of bananas, the accumulated indolic amines will materially affect 

 their physiology. So we may find tliat this topic of indole auxins, 

 which is branching out so rapidly into all fields of plant and agridd- 

 tural jjhysiology, may well find itself in human physiology as well. 



Dr. Fawcett: There are two papers wliich give evidence that in- 

 dolcpropionic acid occurs in Brassica species (Planta 44: 103, 1954; 

 Planta 50: 557, 1958) . Althougli conversion of indolepropionic acid 

 to indoleacrylic acid occurs in human metabolism, there is no evi- 

 dence from our work that this occurs in pea or wheat metabolism. I 

 have syntiiesi/ed indoleacrylic acid, and when it is chromatographed 

 on paper with ;ni acjueous 20 per cent potassiimi chloride solution, it 

 has an Rf of 0.1 1. Hie imknown comj)ound we found in the metabo 

 lism experiments has a much higher R, in this solvent (about 0.67) 

 so thai it appaicMitlv is not indolcac i ylic acid. 



